5th gear doesn’t accelerate…
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Instructor
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5th gear doesn’t accelerate…
Looking to see what others experience here. While ripping down the highway my c8 blasts through 1st -4th, once I hit 5th gear there is definite reduction in power/acceleration. Is 5th gear just geared that way?
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May 22, 2022, 08:13 AM
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5th is not an overdrive on this transmission. It takes you from ~ 112 - 150. It's a longer gear, but not an over drive. The power band isn't wide enough for this transmission to pull a lot of top end. In the Z06 5th is roughly 140-185 and that's with a bigger over all ratio.
Racer
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How fast are you going when your flooring it in 5th? I believe 5th gear maxes out at around 160-170 MPH so you would have to be going pretty fast to get the RPMs high enough to where it will pull like the lower gears.
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Safety Car
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From: N.E. Suburb MN
5th is not an overdrive on this transmission. It takes you from ~ 112 - 150. It's a longer gear, but not an over drive. The power band isn't wide enough for this transmission to pull a lot of top end. In the Z06 5th is roughly 140-185 and that's with a bigger over all ratio.
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5th is not an overdrive on this transmission. It takes you from ~ 112 - 150. It's a longer gear, but not an over drive. The power band isn't wide enough for this transmission to pull a lot of top end. In the Z06 5th is roughly 140-185 and that's with a bigger over all ratio.
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5th is not an overdrive on this transmission. It takes you from ~ 112 - 150. It's a longer gear, but not an over drive. The power band isn't wide enough for this transmission to pull a lot of top end. In the Z06 5th is roughly 140-185 and that's with a bigger over all ratio.
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Safety Car
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From: N.E. Suburb MN
In a C7 7spd 4th gives you 3.42(3.42:1:1)......
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From: Wylie TX
Anything higher than 1:1 in the transmission is not considered an overdrive gear. With your math the car doesn't have any over drive gears. Even 8th 0.33:1 = 1.70:1
Last edited by SECLT22021; May 22, 2022 at 11:10 AM.
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It does not change the fact of how I am driving the driveshafts prior to the rear gear - overdriving or under driving it.
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From: Bay Area CA
Although 4th gear (.88) is an overdriven gear itself, however the addition of the DCT's transfer gear, the overall multiple is 4.56. 5th gear overall multiple is 3.36 on a Z51 and 3.18 on non Z51 which now becomes overdrive. Short story, overdrive in a C8 starts in 5th gear because of the overall gear multiples.
C8
Trans gear x differential gear (3.55) x transfer gear = overall gear ratio. Any overall gear ratio below 3.55 is overdrive.
C7
Trans gear x differential gear (3.42) = overall gear ratio. Any overall gear ratio below 3.42 is overdrive.
C8
Trans gear x differential gear (3.55) x transfer gear = overall gear ratio. Any overall gear ratio below 3.55 is overdrive.
C7
Trans gear x differential gear (3.42) = overall gear ratio. Any overall gear ratio below 3.42 is overdrive.
Last edited by Mike's LS3; May 22, 2022 at 11:18 AM.
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Pro
Joined: Jan 2014
Posts: 703
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Although 4th gear (.88) is an overdriven gear itself, however the addition of the DCT's transfer gear, the overall multiple is 4.56. 5th gear overall multiple is 3.36 on a Z51 and 3.18 on non Z51 which now becomes overdrive. Short story, overdrive in a C8 starts in 5th gear because of the overall gear multiples.
C8
Trans gear x differential gear (3.55) x transfer gear = overall gear ratio. Any overall gear ratio below 3.55 is overdrive.
C7
Trans gear x differential gear (3.42) = overall gear ratio. Any overall gear ratio below 3.42 is overdrive.
C8
Trans gear x differential gear (3.55) x transfer gear = overall gear ratio. Any overall gear ratio below 3.55 is overdrive.
C7
Trans gear x differential gear (3.42) = overall gear ratio. Any overall gear ratio below 3.42 is overdrive.
ttps://www.freeasestudyguides.com/gear-ratio.html
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From: Garden Valley CA
I agree with the above. But the term overdrive doesn't have much meaning with respect to performance these days.
In the "early" days the output ratio of the highest gear in the transmission was 1:1. There were separate overdrive units would make the output shaft turn faster than the input shaft which enabled higher speeds top speeds with low (high ratio) rear end gearing. Then transmissions started coming with additional higher gears that turn the output shaft faster than the input shaft and these were referred to as overdrive transmissions and overdrive gears which is consistent with the definition. Whether or not a gear is an overdrive gear these days doesn't have much meaning. What is important is to have the transmission in the correct gear for the conditions.
In the "early" days the output ratio of the highest gear in the transmission was 1:1. There were separate overdrive units would make the output shaft turn faster than the input shaft which enabled higher speeds top speeds with low (high ratio) rear end gearing. Then transmissions started coming with additional higher gears that turn the output shaft faster than the input shaft and these were referred to as overdrive transmissions and overdrive gears which is consistent with the definition. Whether or not a gear is an overdrive gear these days doesn't have much meaning. What is important is to have the transmission in the correct gear for the conditions.